Nest installation question

[xyz123]

Hi

In slightly unusual situation.

I have a conventional boiler with 7 day honeywell digital programmer. There is wired thermostat in hallway and hot water tank upstairs.

I have got somebody to come and install nest (am clueless with these things so don't want to take a chance) in two weeks.
However todsy looks like my honeywell programmer has developed a fault which is random but needs the controller replacing.

Question is when nest is installed, is the honeywell programmer kept or is it removed? If it is to be removed I don't want to spend £70 odd just for couple of weeks (we r not without water or heating as the problem is intermittent and seems to be resolvable by switching back light off..)

Thanks

[xyz123]

Forgot to aff that installer is on holiday so can't get hold of him at the moment.

[Rollin]

https://nest.com/uk/support/article/What-should-I-...

Seems to suggest it will be removed.

[nyt]

My Honeywell programmer was removed (Worcester Bosch boiler) but I suspect that it's boiler specific.

If the boiler had supported multiple zones then I would have kept it as a backup to the Nest.

[Alucidnation]

I think most built in boiler programmers are an optional extra so he will disconnect and bypass that with the nest wiring.

[stanwan]

The 3rd gen nest has a relay box that will call for heat and hot water. It should replace the programmer completely. Make sure it’s not too far away from the stat to avoid losing connections.

It at all possible connect the two with a low voltage cable.